Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine vane and blade assemblies to high temperatures. As a result, turbine vanes and blades must be made of materials capable of withstanding such high temperatures, or must include cooling features to enable the component to survive in an environment which exceeds the capability of the material. Turbine engines typically include a plurality of rows of stationary turbine vanes extending radially inward from a shell and include a plurality of rows of rotatable turbine blades attached to a rotor assembly for turning the rotor.
Typically, the turbine vanes are exposed to high temperature combustor gases that heat the airfoil. Likewise, the endwalls of the turbine vanes are exposed to the same high temperature combustor gases. It has been determined that fouling negatively impacts the ability of film cooling holes to provide a protective layer of cooling air immediately outward of the inner and outer endwalls, as shown in FIGS. 1-7. In particular, aft impingement pockets have been determined to collect debris and to clog and plug film cooling holes extending from the aft impingement pockets to an outer surface. The plugged film cooling holes cause high thermal gradients to form during operation and shortened lifespan of the endwall.